1. Field of Invention
The present disclosure pertains to the field of traction bars for automobiles.
2. Background of the Invention
A vehicle's suspension is a system of springs (or other shock absorbers) and mechanical links that connects a vehicle's frame with its wheels (including axles). While the vehicle is moving, the suspension allows relative motion between the frame and wheels to isolate the vehicle's occupants from bumps and vibrations encountered by the wheels over the roadway. Suspensions have advanced to the point of vehicle occupants expecting a “smooth” and comfortable ride.
Despite the desirability of a smooth ride for a vehicle's occupants, relative motion between a vehicle's frame and wheels is not always wanted. In particular, certain rotational motions of the vehicle's axle housings relative to the vehicle's frame can be deleterious to the vehicle. Such unwanted relative rotational motion can occur when the torque applied through the vehicle's drive train for forward rotation of the vehicle's tires causes a corresponding twist of the axle housings in the opposite direction from tire rotation. This twist of the axle housings is known as “axle wrap.” Although the vehicle's suspension deflects or absorbs some of the forces resulting from axle wrap, axle wrap nevertheless creates stresses that can damage the vehicle. Furthermore, when high torques are applied through the drive train (e.g., during towing or drag racing) axle wrap can overload the suspension to create another problem called wheel hop, which is a release of the overloaded forces in the form of a violent vertical action of the tires. During wheel hop, the tires jump off the ground so the tires can spin freely and when the tires meet the ground again, the drive axles and suspension are hit with increased torque and possibly repeated wheel hop.
It comes as no surprise that apparatuses have been developed to prevent axle wrap and wheel hop. One apparatus developed for this purpose is a traction bar or colloquially, a “t-bar.” A t-bar is rigid bar that is mechanically connected between a vehicle's axle housings and frame to resist rotation of the drive axle housings relative to the frame. See, e.g., U.S. Pat. No. 3,788,629 by Johnson, which discloses a vehicle traction bar that prevents wheel hop. Although capable of resisting axle wrap and wheel hop, heretofore known t-bars restrict all relative motions, even desirable motions, between the vehicle's frame and wheels. This means that a t-bar sacrifices a smooth ride to avoid axle wrap or wheel hop.
In view of the foregoing, there exists a need for traction bars that restrict wheel hop and axle wrap, while still allowing a smooth ride (e.g., full range of motion in the vehicle's suspension. One attempt at such a traction bar is U.S. Pat. No. 7,918,469 by Hoppert. This traction bar is defined by a combination of a rear spring spacer block and a traction bar that eliminate wheel hop and axle wrap while maintaining a level vehicle drive height. The traction block features a traction bar that is pivotally coupled to a height selected set of spacer blocks that are positioned between the vehicle's spring assembly and axle mount. Hoppert's bar is configured to accommodate vehicles of different lengths but, in operation, the bar applies a rigid connection between the drive axle and the vehicle frame while allowing relative motion of the suspension. Hoppert's bar is not always a satisfactory solution to the above identified need because the bar replaces the vehicle's suspension instead of incorporating the existing suspension. Thus, a need still exists for a t-bar that restricts wheel hop and axle wrap, while still allowing full range of motion of the vehicle's existing suspension.